A crossbar switch is a switch that operates to connect any one of a first plurality of signal ports to any one of a second plurality of signal ports. Generally, signal ports in the first and second pluralities of signal ports are bi-directional and any port in the crossbar switch can be used to both receive and transmit signals. The crossbar switch operates as a router that routes a signal received on any one of its ports in the first or second plurality of ports to a desired port of the second or first plurality of ports from which the signal is transmitted.
Crossbar switches are typically used, for example, for routing signals in communications networks such as a LANs and WANs and in routing data signals between processors comprised in parallel data processing systems. In many situations signals that are routed from an input port to an appropriate output port are optical signals and routing is accomplished by optical crossbar switches. An optical crossbar switch is described in an article entitled “Intelligent Crossbar Switch for Optical Telecommunications based on Micro-Mirror Array” available at URL “www.ece.wpi.edu/˜leblebic/switch/” in September, 2000.
U.S. Pat. No. 5,793,520 to Stace, et al. describes an optical crossbar switch for transferring a light image from an array of input optic fibers to an array of output optic fibers. The switch uses arrays of lenslets and a spatial light modulator to perform switching of optical signals from the input fibers to the output fibers.
U.S. Pat. No. 5,524,153 to H. Laor describes a crossbar switch comprising first and second arrays of optical fibers. Any fiber in the first array can be optically aligned with any fiber in the second array by bending the fibers so as to point an end of each of the fibers so that they are optically aligned facing each other. Bending of a fiber so as to point its end in a desired direction is accomplished by two piezoelectric benders that bend the fiber near the end about two orthogonal axis. Ends of two fibers are optically aligned responsive to intensities of optical alignments signals that are generated by radiation emitting devices located at known positions with respect to each of the ends of the fibers.